Analysis of joint fluid particulates has revealed collagen types I and III in patients with rheumatoid arthritis and systemic lupus erythematosus and type II in patients with severe osteoarthritis. The types and total quantity of collagen in joint fluid pellets will be correlated with the clinical diagnosis, synovial fluid oxygen partial pressure and other clinical, radiologic and serologic parameters to test the hypothesis that collagens type I and III are derived from microinfarction of the rheumatoid (or lupus) synovium. Needle-shaped hydroxyapatite crystals occurring in clumps, approximately 3-19 microns in diameter (microspheroids by scanning electron microscopy), active collagenase and neutral protease have been found in joint fluids from 7 of 8 shoulders of patients with rotator cuff defects. The pathogenesis of this syndrome is being investigated.